Ignition system



Dec. 1 1, 1945. G. H. MARMONT 2,390,542

IGNITION SYSTEM Filed Aprilv29, 1944 r IN V EN TOR. 650B 6 E H MHEMO/V7- t9 7" TO/ENE Y causing it to sweep over the contacts.

Patented Dec. 11, 1945 IGNITION SYSTEM George H. Marmont, Detroit, Mich,asslgnor to Bendix Aviation Corporation, Detroit, corporation ofDelaware Mich. a

Application April 29, 1944, Serial No. 533,383

4 Claims.

This invention relates to ignition systems, and more particularly to anignition system for an internal combustion engine.

Broadly the invention comprehends an ignition system for a prime moverincluding a cathode ray tube having a heated cathode, an arrangement ofa electrodes serving to attract electrons from the cathode and toproject them in a beam, a distributor including oriented contacts, and amagnet for deflecting the electron beam and The contacts are spaced tocorrespond to the firing times of the cylinders of the prime mover andare connected through relay circuits to the spark plugs in the heads ofthe cylinders.

An object of the invention is to provide an ignition system for aninternal combustion engine including means for utilizing a low currentto trigger a circuit carrying high voltage operative to discharge acrossthe gap of a spark plug.

Another object of the invention is to provide an ignition system for aninternal combustion engine characterized in that an electron beam isutilized to successively trigger a series of high voltage circuits, eachoperative to discharge across the gap of a spark plug.

Another object of the invention is to provide an ignition system for aninternal combustion engine characterized in that an electron beam may bedeflected to sweep over oriented contacts connected to a series of highvoltage circuits so as to successively trigger the circuits and cause adischarge across the gaps of spark plugs.

A further object of the invention is to provide an ignition system foran internal combustion engine characterized in that an electron beamdeflected by the poles of a rotatable magnet geared to the crankshaft ofthe engine serves to successively trigger relay circuits so as to causedischarges therefrom across the gaps of spark plugs associated with theengine.

Yet a further object of the invention is to provide an ignition systemfor an internal combustion engine characterized in that an electron beinduced in the secondary of the transformer to cause a discharge acrossthe gap of a spark plug.

Other objects and advantages of the invention will appear from thefollowing description taken in connection with the drawing forming apart of this specification, and in which:

Fig. 1 is a longitudinal sectional view illustrating the control for anignition system em bodying the invention; and

Fig. 2 is a dlagratical illustration of the system.

Referring to the drawing for more specific details of the invention, 6 trepresents a shaft which may be suitably geared to the crankshaft of aninternal combustion engine. The shaft it is connected through aconventional timer [12 to a spindle it supporting a magnet it forrotation therewith. U

A stationary shell or case it of magnetically shielding materialenclosing the magnet it has suitably secured therein a collar 2d of anydesirable insulating material, and binding posts 22 are arranged on thecollar in spaced relation to one another. A metallic shell 26} fixedlysecured to the collar 29 extends therefrom concentrically of the casebetween the poles of the ma net it, and a base 126 is fitted in theshell.

A cathode ray tube 28 having the characteristics of the tube describedin my co-pending application flied on even date herewith, is fitted onthe base 2% in the shell 26 and is supported by the collar 2@. I'he tubehas thereon a base Mi received by an opening in a cover plate 32 on thecase it.

A cable 3 3 leading from a suitable source of electrical supply extendsthrough an opening in the cover plate 32 into the case it, and the leads36 thereof are connected to the binding posts 22, which in turn areconnected by leads it to the sockets of the base 28 receivingthe tube,and another cable at leading to a group of electrical circuits, to behereinafter described, extends through a cap d2 fitted on the base 30protruding through the cover plate 82 of the case it, and the leads t6thereof are connected to sockets for the reception of the plugs in thebase 30.

As shown diagrammatically, the cathode ray tube 28 includes a heater at,a cathode 48, a grid 50, and a group of anodes E2 constituting anelectron gun which serves to attract electrons from the cathode andtofocus them in a beam down the axis of the tube, and the magnet 66rotating around the tube serves to deflect the beam.

The cathode ray tube is characterized in that a distributor 54 supportedin the tube has thereon a plurality of spaced distributor plates 56 overwhich the focused electron beam sweeps when deflected by the poles ofthe magnet as the poles rotate about the tube.

Each distributor plate 58 is connected to a relay circuit as by a lead6t. Since these relay circuits are identical, a description of one willsuillce for all.

As shown, a tube as of the thyratron type includes a heater as forheating a cathode 66, a shielded grid 68, and a plate 10. The lead tilis connected to the grid as. The plate 70 is connected to one terminalof a condenser 12. The plate it is also connected to a source ofsubstantially constant voltage it by a resistor 76. The other terminalof the condenser 12 is connected to one terminal of the primary 78 of atransformer 8t, and the other terminal of the primary is grounded at 62.The cathode 86 is also grounded at 82. The grid 681s connected to asuitabl source of negative bias 8t by a grid leak resistor 86. The gridis also by-passed to ground by a small condenser (iii. The secondary 90of the transformer Eli has its terminals connected to a spark plug 92,and a capacitance 9Q represents the stray capacity of the secondary 99of the transformer and its leads to the spark plug.

In the circuit illustrated, the plates 58 of the I distributor tubeassume a positive potential, due

to secondary electron emission from the plates, 1

when the electron beam impinges on the plates. This action causes theplate 8b to assume a more positive potential when the electron beampasses over its plate. The grid as is thereby driven sufilcientlypositive, relative to its bias potential, to turn on the thyratron 62.

It is to be understood that with other types of gas tubes, such as acold cathode tube, an ade quat negative pulse from the distributor wouldbe effective for purposes of triggering the gas tube. The distributorshown is capable of producing such negative pulses when the properpotential is applied to the distributor plates.

The characteristic of a thyratron tube is that. once turned on,conduction continues until the anode or plate potential oi the tubereaches a certain minimum value. While conducting, it possesses a lowresistance. Therefore, if, as shown in the drawing, a charged condenserand the primary of a transformer 8B are connected in series with thetube, the condenser will discharge through the'transformer 8t and tube,when the latter is turned on, with a very small loss of ensource It.

While this invention has been described in connection with certainspecific embodiments, the principle involved is susceptible of numerousother applications that will readily occur to persons skilled in theart. The invention is. therefore, to be limited only as indicated by thescope of the appended claims.

Having thus described the various features of the invention, what Iclaim as new and desire to secure by Letters Patent is:

1. An ignition system for an internal combustion engine comprising meansfor projecting an electron beam, a distributor having oriented contacts,means driven by the engine for moving the beam successively over thecontacts, a relay cir= cult connected to each oi the contacts. and aspark plug coupled to each relay circuit.

2. An ignition system for an internal combustion engine comprising meansfor projecting an electron beam, a distributor having oriented contacts,magneticmeans driven by the engine for moving th beam successively overthe contacts, a relay circuit connected to each of the contacts. and aspark plug coupled to each relay circuit.

3. An ignition system for an internal combustion engine comprising meansfor projecting an electron beam, a distributor having oriented contactsthereon, magnetic means driven by the engine for sweeping the beam overthe contacts, relay circuits connected to the contacts, each circuitincluding a tube, a condenser and the primary of a transformer connectedin series, and a large resistance connected to a positive potentialsource, and a spark plug connected to the secondary of the transformer.1

4. An ignition system for an internal combustion engine comprising astationary case, a shaft driven by the engine, a stub shaft rotatable inthe case, a timer connecting the shafts, a shielded tube supported inthe case, a magnet on the stub shaft rotatable around the tube, a heatedcathode in the tube for supplying electrons, at gun for attracting theelectrons from the cathode and projecting them in a beam, a distributorhaving thereon oriented contacts successively receiving the beam as itsweeps over the distributor under the influence of the magnet, a relaycircuit connected to each of the contacts, each circuit'ineluding atube,a condenser, and the primary of a transformer connected in series and alarge resistance connected to a positive potential source, and a sparkplug connected to the terminals of the secondary of the transformer.

GEORGE H. MARMONT.

